The question asks for the intersection of two sets $A$ and $B$.

Given:

• $A = \{2, 3, 5, 7\}$
• $B = \{5, 7, 9, 11\}$

Finding $A \cap B$ (the intersection):

The intersection of two sets includes only the elements that are common to both sets.

• Elements in $A$: $2, 3, 5, 7$
• Elements in $B$: $5, 7, 9, 11$
• Common elements: $5, 7$

Thus, $A \cap B = \{5, 7\}$.

Answer:

The correct choice is B. $\{5, 7\}$.

Would you like further clarification or additional examples?

5 Related Questions:

1. What is the union of $A$ and $B$?
2. How would the intersection change if $A = \{3, 5, 7\}$?
3. What is the difference $A - B$?
4. How does set intersection differ from set union?
5. Can two sets have an empty intersection? When does this occur?

Tip:

To find the intersection of two sets, always look for elements that are present in both sets.